1. Field of the Invention
The present invention relates to a dimpleless tube cutting apparatus for use in a continuous tube manufacturing plant wherein a coiled strip is made into a continuous tube, for accurately cutting the tube into desired lengths while a cutting assembly is traveling.
2. Description of the Prior Art
In a tube manufacturing plant, a coiled strip is formed into a continuous tube by a continuous operation. The continuous tube formed is cut by a traveling cutting apparatus into desired lengths with minimized errors in accordance with the contemplated use.
While such apparatus are known, for example, in U.S. Pat. No. 4,149,438, it is required to lengthen the distance of travel of a cutting assembly when it is desired to cut the tube at a higher speed with an increase in the speed of production of the tube. Accordingly there arises the need to use a longer ram-and-crank assembly for depressing the cutting assembly during travel and therefore to use more than one crankshaft. To meet this requirement, the apparatus of the present invention, although including a single drive crankshaft, is provided with follower crankshafts for suspending an elongated ram therefrom, with a cutting assembly slidably supported by the ram. When the speed of the cutting assembly, reciprocating under the control of a computer, matches the speed of the tube to be cut, the cutting assembly is positioned for the desired cutoff length, and the ram is depressed exactly at the same time.
With the tube cutting apparatus comprising such an elongated ram and a plurality of crankshafts, the follower crankshafts must be rotated in synchronism with the rotation of the drive crankshaft, so that a train of gears is conventionally interposed between the crankshafts to assure the synchronous rotation. However, the gears, which need to have strenght sufficient to withstand the impact of cutting, give an increased weight to the crankshaft rotary assembly, necessitating a great force for operating the crankshafts when initiating a cutting operation and also necessitating an increased braking force for stopping the crankshafts before the subsequent cutting operation.